1. Field of the Invention.
The present invention relates to the field of angioplasty. In particular, the present invention relates to a dilatation balloon catheter.
2. Description of the Prior Art.
Angioplasty has gained wide acceptance in recent years as an efficient and effective method for treating types of vascular diseases. In particular, angioplasty is widely used for opening stenoses in the coronary arteries, although it is also used for treatment of stenoses in other parts of the vascular system.
The most widely used form of angioplasty makes use of a dilatation catheter which has an inflatable balloon at its distal end. Using fluoroscopy, the physician guides the catheter through the vascular system until the balloon is positioned across the stenosis. The balloon is then inflated by supplying fluid under pressure through an inflation lumen to the balloon. The inflation of the balloon causes stretching of the artery and pressing of the lesion into the artery wall to re-establish acceptable blood flow through the artery.
Two commonly used types of dilatation catheters are referred to as "over-the-wire" and "non-over-the-wire" catheters. An over-the-wire catheter is one in which a separate guide wire lumen is provided so that a guide wire can be used to establish a path across the stenosis. The dilatation catheter can then be advanced over the guide wire until the balloon is positioned across the stenosis. A non-over-the-wire catheter acts as its own guide wire, and thus there is no need for a separate guide wire lumen. A non-over-the-wire catheter can therefore achieve a smaller outer diameter for its main shaft since a guide wire lumen is not required.
There has been a continuing effort to reduce the profile and shaft size of the dilatation catheter to allow the catheter to not only reach, but also cross, a very tight stenosis. A successful dilatation catheter must also be sufficiently flexible to pass through tight curvatures, especially in the tortuous coronary arteries. A further requirement of a successful dilatation catheter is its "pushability." This involves the transmission of longitudinal forces along the catheter from its proximal end to its distal end allowing a physician to push the catheter through the vascular system and across the stenosis.